Due to the rapidly increasing costs and shortages of energy, it is particularly desirable to develop new and more efficient systems which assist in the maintenance of a uniform temperature inside a structure using the heat of sunlight. Such systems are preferably capable of converting the energy available in sunlight to heat the air in a building when the inside temperature is too low and conversely, insulating the inside air from the outside atmosphere when it is desired to stop heat transfer between the inside and outside air. The development of the use of solar energy to achieve this result has been hampered by numerous problems such as installation in existing structures without major renovations or other structural changes to the existing building, size of the unit, cost efficiency, aesthetics, low start up time, etc.
Known solar devices for heating the air in a room, have provided spaced panes of glass as seen in Jacobs, U.S. Pat. No. 4,151,954, and exterior heating panels such as shown in Lorenz, U.S. Pat. No. 4,237,865.
Other known solar heating devices have utilized the venetian blind type panels. Such known devices are disclosed in Pierce, U.S. Pat. No. 4,143,640 and Tisch, et al, U.S. Pat. No. 4,220,137 which disclose louvers which are adjustable to reflect the sunlight impinging thereon to a solar collector.
Yet another known venetian blind type device as disclosed in Angilletta, U.S. Pat. No. 4,002,159, discloses a venetian blind with a heat absorptive surface on one side of the venetian blind slats and a reflective surface on the other side of the slats.
One desirable feature of a solar heat regulating device is to assist in the maintenance of a uniform temperature inside of a building by converting the energy available in sunlight to heat the air in the building when the inside temperature is too low. For example, on a cold, sunny day, the outside temperature may be low but the sunlight is capable of heating. Thus, it is desirable that the solar heat regulating device efficiently transfer the heat from the sunlight to the air inside the building.
Conversely, it is a desirable feature to insulate the inside air from the outside atmosphere during certain periods of time to stop heat transfer therebetween. For example, on a cold day when the sun is not shining, the temperature of the inside air is more effectively held at a uniform level if the amount of heat which can escape from the inside to the outside through the window is minimized. Also, in the summer when the outside air has a greater temperature than the inside air, it is desirable to stop the transfer of heat from the outside air to the inside air.
Another desirable feature of a solar heat regulating device is to maximize the efficiency of the heating and insulating features described above.
Another particularly desirable feature of a solar heat regulating device is that it be capable of being retrofitted into an existing window in an existing building without major renovations or other structural changes to the existing building.
Yet another desirable feature is to provide a device which can be mounted inside of a window of an existing structure so that the device is protected from the elements, can be operated from the interior of the building without any connections to the exterior of the building. This feature also allows for the minimization of installation costs. By mounting the device adjacent to a window and inside the building, it is not necessary to create openings in the building to conduct the heat inside.
Another feature of a solar heat regulating device is that it have simplicity of operation, attractive appearance, and minimal, if any, power consumption in operation.
Another desirable feature of a solar heat regulating device is that it have a low start up time. For example, when units are mounted outside of buildings, the units cool down when not operating in low outside temperatures and require substantial periods to start up when the sunlight contacts them.
Another desirable feature of a solar heat regulating device for window areas is to be capable of intercepting all of the incoming solar radiation but one which, nevertheless, permits visibility through the window.
Another desirable feature is to provide a solar heat regulating device which is relatively economical to construct, operate and install, is small in size and aesthetically pleasing.